November 5, 2017 at 8:48 am #375319JessParticipant
Hi Laura, I was concerned to see a few discussions of an unsafe garlic confit recipe in the forum. I tried to reply to those posts but I didn’t see my posts go through, so I’m posting here to ask you to please revisit those topics with updated safety information.
The method of making a garlic confit in oil in a jar in a pressure canner and then storing it in the refrigerator is unsafe unless the garlic confit is stored in the freezer, NOT the refrigerator. Here’s why:
According to the UC Davis Food Safety flyer, at least 4 outbreaks of foodborne botulism poisoning have occurred from garlic in oil preparations in the USA, either commercial or home made. http://ucfoodsafety.ucdavis.edu/files/250352.pdf Cases in Europe are much more common, because people store food in oil more often there.
Non-proteolytic Botulism spores can grow at refrigerator temperatures. They are responsible for most of the botulism poisoning cases that happen. See this industry paper: https://www.news-medical.net/news/20101001/New-method-for-detecting-spores-of-non-proteolytic-Clostridium-botulinum.aspx
The takeaway: IF there are any living botulism spores on the garlic after pressure cooking, it is NOT safe to store it at refrigerator temperature. You have to freeze it. Botulism spores do not grow and produce toxin at freezer temperatures. http://extension.missouri.edu/p/GH1501
The thing is, it is possible that their method might destroy botulinum spores, but only if they use very high temperature for a long time. The UCSB Science Line website says “C. botulinum spores can be killed by heating to extreme temperature (120 degrees Celsius) under pressure using an autoclave or a pressure cooker at for at least 30 minutes.” http://scienceline.ucsb.edu/getkey.php?key=1307
Wikipedia says that at a pressure of 1 bar or ~15 psi (pounds per square inch) above the existing atmospheric pressure, water in a pressure cooker can reach a temperature of up to 121 °C (250 °F), depending on altitude. However, the Instant Pot electric pressure cooker has a highest working temperature of only between 115 and 117 degrees Celcius (at sea level) according to this page posted by the manufacturer: http://instantpot.com/which-electric-pressure-cooker-operates-at-15psi/
So no amount of time in an Instant Pot is going to destroy a botulinum spore, and that’s not even taking into account the insulating effect of the oil. Of course some pressure cookers go to a higher temperature, but you need to factor in the oil-insulating effect as well.
The bottom line: If you make this, you should freeze it. Because botulinum spores are rare, you could get away with using an unsafe preparation/storage method for a long time, and then one day you could kill someone. In my opinion, it is irresponsible to take that risk when you could easily prevent that hazard by freezing your product instead of refrigerating it.
Thank you!November 5, 2017 at 8:51 am #375666Laura PazzagliaKeymaster
Hi Jess, new posters have their first messages moderated. I have checked your replies and approved them. Thanks for sharing this new information with us. I’m definitely going to read the references you provided.
Welcome to the forums!
P.S. Have you contacted Modernist Cuisine with this information?November 5, 2017 at 5:28 pm #376004JessParticipant
Thank you. Yes, I have posted in the comments under the recipe on the Modernist Cuisine website. However, they had already replied to previous comment by saying that they’ve always done it that way and never had a problem, an answer that I find disturbing and irresponsible. Using an unsafe technique with regard to botulism will almost always be fine because the botulinum bacteria is rare, however risking people’s lives on a gamble that the spores won’t be present is just not ok.
I would like to respectfully suggest that, if you agree after reading the references, you go back and edit your first reply on the garlic confit post to make it clear that this isn’t a safe method. Many people will not read all the way to the bottom and see my post (and of course you have the most credibility with your readers!)
Best wishes, Jessica
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